=== README ===
This support function without params call ala Oracle

CREATE OR REPLACE FUNCTION CURRENT_USER_OID()
RETURNS oid AS $$
  SELECT usesysid FROM pg_user
    WHERE usename = CURRENT_USER;
$$ LANGUAGE sql VOLATILE;

postgres=# select current_user_oid;
 current_user_oid 
------------------
             16384
(1 row)